1. Technical Field
The present invention relates to a robot.
2. Related Art
There is known a robot including an arm in which a plurality of arm members are connected by joints. It is possible to cause the robot to perform various kinds of work by attaching a robot hand and the like to the distal end of the arm. However, when the robot hand or the like is moved to a target position and stopped in order to perform work, the work cannot be started because the distal end of the arm oscillates for a while.
Therefore, there has been proposed a technique for mounting an inertial sensor on the distal end side of an arm and suppressing oscillation of the arm by controlling movements of joints of the arm to reduce an output of the inertial sensor (JP-A-2005-242794 (Patent Literature 1)).
However, among robots including a large number of joints, there is a robot that moves a certain joint to thereby change the directions of rotation axes of the joints ahead of the joint. Even if the technique of Patent Literature 1 is applied to this robot, it is difficult to sufficiently suppress the oscillation of an arm.
This is because, when the distal end of the arm is oscillating, for example, since control contents (a control amount and a control direction) concerning a joint on the distal end side of the arm change according to a rotation position of a joint further on the root side (the base side) than the joint on the distal end side, control is complicated.
When the distal end of the arm is oscillating, usually, the rotation position changes every moment because oscillation occurs even in the joint on the root side. As a result, since the direction of the joint on the distal end side of the arm changes every moment, the control is more complicated. In addition, influences due to deformation of the joints and a machine error accumulate more toward the distal end of the arm. Therefore, if the technique of Patent Literature 1 is applied to the robot having the problems explained above, the oscillation is sometimes amplified to the contrary.
In this way, many problems are left to control oscillation of a robot including a plurality of joints having different directions of rotation axes.